billeter



Feb. 14, 1956 H. R. BILLETER GRINDING DEVICE 4 Sheets-Sheet l Filed Jan.2l, 1953 P @www ww ,ww www w INVENTOR. Iyjzjaeez BY Hen QQN. .QNN

Feb. 14, 1956 H. R. BILLETE-R GRINDING DEVICE 4 Sheets-Sheet 2 FiledJan. 2l, 1953 IN VEN TOR. /engjyja erllezpez w @l .N

Feb. 14, 1956 H. R. BlLLETER GRINDING DEvrcE 4 Sheets-Sheet 3 Filed Jan.21, 1953 Feb. 14, 1956 H. R. BILLETER 2,734,319

GRINDING DEVICE Filed Jan. 21, 1955 4 Sheets-She`e't 4 MEN United StatesPatent O GRHNDWG DEVICE Henry Robert Biileter, Highland Park, Ill.,assigner to Ammco Tools, lne., North Chicago, lli., a corporation ofIllinois Application January 2l, 1953, Serial No. 332,3lil

7 harms. (ci. 51-96) The present invention relates to a grinding deviceand has to do particularly with improvements in a grinding device of thecharacter disclosed and claimed in my prior f application, Serial No.180,425, filed August 19, 1950.

The grinding device to which the present invention relates isparticularly adapted for grinding arcuate contours and especially welladapted for dressing down the exposed arcuate surfaces of automotivebrake shoe linings to produce a true cylindrical face of proper radiusto lit the brake drum with which the brake shoe is to be used.

In processing lined automotive brake shoes it is usually necessary todress down a new lining so that the-radius of curvature is the same asthat of the brake drum with which the brake shoe is to be used in orderthat the entire braking surface of the shoe will engage the brake drumwhen the brakes are applied. When a brake drum becomes worn, it isusually bored out to insure that its braking surface is trulycylindrical and as a result its radius is greater than the radius of thebrake shoe with which it is associated. When an oversize brake lining isapplied to such brake shoe it is usually necessary to dress down thesurface of the brake lining until its exposed curved surface is trulycylindrical, if it was not theretofore cylindrical, and of a properradius to accurately fit the inside surface of the brake drum.

The present invention includes improvements in a device for grindingbrake shoes according to the above considerations, having a rotatablegrinding element, a carriage mounting a brake shoe holder foroscillation relative to the grinding element, means for adjustablymoving the carriage toward and from the grinding element forcorrespondingly adjustably positioning the axis of oscillation of thebrake shoe holder in spaced relation to the grinding element, and meansfor adjustably moving the brake shoe holder relative to the carriage'indirections toward and from the grinding element whereby the brake shoeholder may be adjustably so moved relative to an axis of oscillationfixed relative to the grinding element.

An object of the invention is to provide in a device of the foregoinggeneral character novel means for releasably securing the carriage inadjusted positions.

Another object is to provide a device of character noted having novellocking means for releasably securing the carriage in any of a number ofpredetermined spaced positions and novel means for releasably retainingthe locking means in disabled position.

Still another object is to provide a device of the character referredto, having novel locking means for releasably securing the carriage inany of a number of predetermined spaced positions, means for releasablyretaining the locking means in disabled position, and means serving toindicate to the operator the positioning of the carriage in any of thepredetermined positions, facilitating movement of the locking means tolocking position.

A further object is to provide a device of the above general characterhaving means for effecting line adjustments of the carriage relative toany of its predetermined spaced 2,734,319l Patented Feb. 14, 1956 Ficepositions, in which the adjusting means is of novel constructionfacilitating its setting to zero position.

Still another object is to provide a device of the foregoing characterhaving novel means for stably mounting thebrake shoe holder on thecarriage in such a way as to effectively withstand tendency todisplacement of the holder relative to the grinding element so as topreserve proper alignment of the brake shoe held in the holder relativeto the grinding element.

Another object is to provide in a brake shoe grinder, a grinding elementof novel construction including a cylindrical abrasive sleeve, and meansfor retaining the sleeve in accurate, predetermined dimensions.

A further object is to provide a brake shoe grinder having a grindingelement including a flexible, cylindrical abrasive sleeve, and means forsupporting the flexible sleeve in the form of an inner sleeve yieldablyexpansible in directions for increasing its diameter but capable ofVbeing rigidly held against deflection from substantially cylindricalshape.

Another object is to provide a brake shoe grinder having a rotatablegrinding element and a housing at least partially surrounding thegrinding element, and means for collecting dust from the housinggenerated by a grinding operation, in which novel means is provided forsealing the portion of the housing in which the grinding element rotatesagainst the emission of dust therefrom.

Other objects and advantages of the invention will be apparent from thefollowing detail description taken in conjunction with the accompanyingdrawings in which- Fig. l is a side elevational view of a brake shoegrinding apparatus constructed in accordance with the principles of thepresent invention, certain of the parts being shown as brokenlaway andothers sectioned to more clearly reveal the nature of the invention;

Fig. 2 is-a top plan view of the apparatus;

Fig. 3 is a front elevational View thereof;

Fig. 4 is an enlarged, fragmentary cross-sectional view takenapproximately on the line 4-4 of Fig. 1;

Fig. 5 is an enlarged fragmentary view taken substantially on line 5-5of Fig. l;

Fig. 6 is'an enlarged fragmentary sectional view taken substantially online 6 6 of Fig. 2;

Fig. 7 is a cross-sectional view taken on line 7-7 of Fig. 6;

Fig. 8 is atop plan view of the lower brake shoe clamp, with brokenlines showing somewhat diagrammatically the relative positions taken bytwo brake shoes of dilerent sizes when in position in .the clamp; and

Fig. 9 is a side elevational view of the lower brake shoe clamp andshowing also a portion of the upper clamp and somewhat diagrammaticallya brake shoe in position in the clamps.

The grinding device of the present invention is especially well adaptedfor grinding to true cylindrical contour the surfaces of liningsattached to automotive brake shoes and the device is described herein inconnection with such use for the purpose of illustration. It will beunderstood that the invention is not thus limited and that theprinciples may be applied to other uses where generally similar resultsare desired.

Referring now to the drawings in detail and in particular to Fig. l, thegrinding device includes a base or frame l0 in the form of an elongatedrectilinear casinglike member having a base flange i2 extendingtherearound from which there extends upwardly and inwardly, preferablyat a slight taper, a pair of side walls 14 and 16, a front wall l and acurved rear wall 2l). The top wall 22 of the structure constitutes a bedplate upon which is mounted the principal operating elements of the.apparatus. The ange l2 is formed with a plurality of supporting feetorfpads 24 by means of which the base 10 may be secured to a supportingsurface such as a Work bench, with the flange 12 slightly elevated fromthe surface thereof to permit circulation of air beneath the apparatusfor purposes that will become apparent presently.

Supported within anopening 25 (Fig. l) formed inthe top wall of the base'10 is an electric motor M which is suitably secured to the base as bymeans of a mounting bracket 27 and bolts 26. Current may be supplied tothe motor by means of a cable 28 and a conventional switch assembly 30is provided to control the motor circuit. The motor M serves to drive agrinder 47 of novel construction adapted to dress down the surface of abrake shoe lining and hence is provided with a shaft 32 which projectsdownwardly in the base 10 and carries a driving pulley 34 thereonoperatively connected by a driving belt 36 to a driven pulley 38 mountedon a vertically extending shaft or spindle 40 which projects through anopening in the bedplate 22 of the base 10. rPhe shaft 40 is mounted inupper and lower antifriction bearings 42 and 44, respectively, carriedin a boss 46 formed in the bed plate. The shaft40 projects upwardlyabove the bed plate and detachably carries at its upper portionthegrinding element 47 referred to above and shown in detail in Figs. 6and 7. The grinding element includes an inner sleeve 48 of substantiallycylindrical form having an axially extending slot 49 throughout itslength. The sleeve 48 is preferably of aluminum and, as such, isrelatively rigid with respect to resistance to deection in localizedareas, but due to the provision of slot 49, the sleeve has a limiteddegree of yieldability in that it can be slightly expanded so as toincrease its diameter beyond its normal diameter. The sleevecontractsand assumes a normal relatively small diametler when it is dismountedfrom the shaft in which the slot 49 may be substantially closed or atleast reduced in dimension in circumferential direction. When thealuminum sleeve is placed on the shaft it is slightly expandedin'diameter whereby the slot 49 is slightly widened vand the sleeve inthe expansion thereof comes into engagement with the outer abrasivesleeve 50 for frictionally supporting thel abrasive sleeve andmaintaining it in true cylindrical form. The outer abrasive sleeve 50 ispreferably made up' of a relatively flexible material such as a web withabrasive material Aon its outer surface. rThe abrasive sleeve may beformed as'by wrapping a strip of material on a suitable'form andsecuring the adjacent convolutions together as' by adhesive material,`and preferably` the abrasive sleeve consists of several layers insuperposed relation. The completed abrasive sleeve thus has a normalcylindrical shape of nominal dimensions although it is relativelyflexible and 'may be deformed.

The inner sleeve 48 has a normaldiameter slightly less than the nominaldiameter of the abrasive sleeve and the means for mounting the aluminumsleeve produces an expansion of the aluminum sleeve so that itfrictionally and tightly engages the abrasive sleeve and maintains it intruly cylindrical shape and of the desired ultimate dimension.

The means for mounting the sleeve assembly made up of the inner sleeve48 and outer sleeve 50 includes a lower washer 51 and an upper washer52, the lower washer being secured to the shaft`40 for rotationtherewith by suitable means such as a pin 53 extending diametricallythrough a hole in the hub of the washer and shaft. The lower washer 51is adapted to rest on the upper'bearing 42 and thereby serves as ameansl for supporting the shaft 1n axial position. The upper washer 52has a recess 54 adapted to snugly receive the upper end of the shaft anda smaller diameter aperture 55 for receiving the shank of a screw 56,the aperture being surrounded by an inturned flange 57. The screw shankis threaded for threading into a tapped hole in the shaft, and isprovided with a projection 58 fitted in an enlarged portion 59 of therecess in the shaft, and a knurled head portion 60.

The washers 51 and 52 include central portions'61 having chamfered edgesurfaces 62, and outwardly from the chamfered surfaces are cylindricalsurfaces 63 terminating in shoulders 64 defined by radial flanges 65 ofrelatively small radial dimension.

The sleeves 48 and S0 are mounted by placing them in assembled,telescope condition over the upper end of the shaft into engagement withthe lower washer 51, the inner sleeve 48 engaging a chamfered surface 62on the lower washer. The upper washer 52 is then fitted over the sleevesand the screw 56 is threaded into the tapped hole in the shaft whichforces the upper washer downwardly and the two washers relatively towardeach other. The chamfered surfaces 62 on the two washers expand thesleeves to the dimension determined by the cylindrical portions 63,whereupon expansion of the sleeves ceases and continued threading of thescrew 56 brings the shoulders 64 into engagement with the ends of thesleeves. The sleeves are then rigidly mounted in assembly, the tendencyof the aluminum sleeve 48 to contract acting to establish the desiredfrictional engagement between that sleeve and the washers for therotation of the sleeve on the shaft. The engagement of the shoulders 64with the aluminum sleeve limits the movement of the washers toward eachother and establishes a firm and solid assembly. The recess 5ft-receivesthe upper end of the shaft and hence the upper washer 52 is positionedconcentric with the shaft for true rotation of 'the sleeve with theshaft. The collar or projection 58 serves to engage the flange 57 inremoving the screw 56 from the shaft whereby a positive force isprovided for removing the upper washer 52 from the shaft and therebyfrom the sleeve assembly. The grinding element 47 when assembled on theshaft as above described forms -a rigid cylindrical grinding wheel whichserves to accurately grind the brake shoe in conjunction with theaccurate positioning of the brake shoe relative to the grinding element.

A hood 66 having an'o'pen front 67 is removably secured to the base 1l)as by means of wing fastening studs 68 (Fig. 2) and substantiallyencloses the grinding element 47. The interior of the hood 66communicates through a series of openings 69 with the interior of anannular suction chamber 70 surrounding the boss 46 beneath the bed plate22 and defined between the boss 46 and a depending circular flange 71integral with the bed plate. A second circular ange 72 formed on the bedplate depends therefrom and surrounds the circular flange 71 lto definetherewith an annular dust-collecting chamber 73. A ring-like cover plate74 is removably secured to the flange 72 and encompasses the drivenpulley 38 and `serves as a closure for the dust-collecting chamber 73.Preferably the cover plate 74 closely approaches the hub ofthe pulleyand above the cover plate is an impeller 75 disposed in the chamber 70and preferably consists'of a sheet metal stamping including a disc-likeportion 76 and blade elements 77. The impeller may be secured in placefor rotation with the pulley and shaft by securement between the pulleyand bearing 44. The impeller 75 serves to draw air and the comminutedproducts of abrasion from the hood`66 into the suction chamber 70, andto expel the same by the action of centrifugal fo'ceintothedust-collecting chamber 73. The chamber 73'comrr`iunica'tes with anelbow device 79 (Fig. 2) which projects through the side of the wall ofthe base and to whichthe're 'is removably attached by means of a garterspring a dust-impervious but porous dust-collecting bag 81.

lIn order to seal the suction chamber 70 and the dustcollecting chamber73 against the efliux of dust and coniminut'ed'inaterials around theshaft 40, the pulley 33 is provided with a seal 82 in the form of a ringof resilient material'fitted in an annular groove in the pulley landengaging the undersurface of the cover plate 74. The resilient sealingring '82 is of greater 4diameter than the central opening in the coverplate 74 and, being in 'yielding engagement with the cover plate, sealsthe chamber 70 againstthepassage of dust around the shaft.

Referring now to Figures 4 and 6, a carriage 83 is slidably disposed onthe upper surface of the bed plate 22 for adjustable movement toward andaway from the grinder 47. The carriage 83 is formed with an arcuateupper surface 84 (Fig. 4) of relatively long radius of curvature, whichsurface is formed with a flat circular turntable bed or supportingsurface 85 (Figs l and 6) on which there is rotatably disposed acircular turntable 86 forming part of a pivoted carriage 87 adapted tosupport a brake shoe holder S8. The carriage 87 pivots about a pivotaxis established by a pivot pin 170 as explained more in detailhereinafter.

The carriage 83 is provided with downwardly extending slide rails S9(Fig. 4) which rest upon slide rails 90 which project upwardly from andextend longitudinally of the bed plate 22. A continuous marginal flange91 overlies the edge of the top wall 22 and serves to protect the rails89 and 90 against the accumulation of the products of abrasion.

The bed plate 22 is formed with an integral longitudinally extendingdepending rib 92 having a longitudinal groove 92a formed in its uppersurface, and the carriage 83 is formed with a longitudinally extending,depending rib 93 having a longitudinal groove 93a in its lower surfaceand in register with the groove 92a. An indexing bar 94 which isrectangular in cross section is slidably disposed in and enclosed withinthe grooves 92a and 93a and serves in the manner of a key or guide railto align the carriage 83 on the bed plate 22 in proper cooperatingrelationship with respect thereto, while at the same time permittinglongitudinal adjusting movement of the carriage 83 on the bed plate 22in a direction toward and away from the grinder. The indexing bar 94constitutes the sole means for guiding the carriage d3 against thelateral displacement on the bed plate 22. It also serves as an elementof the indexing means hereinafter described for selectively positioningthe carriage 33 in any one of a plurality of spaced, predeterminedpositions on the base 19.

The indexing bar 94 has formed therein a series of longitudinally spacedaligned openings or index holes 9S, each of which is bell-mouthed at oneend as at 96 (Fig. 5), and provided with a relatively short bevel ortaper 97 at the other end. The holes 95 are adapted upon movement of theindexing bar 94 to be selectively brought into register with the innerend of an indexing or locking pin 93 which is slidably disposed in abore 99 formed in the rib 92 and opening into the groove 92a and in abore 100 formed in a side wall 14 of the base ld. A coil spring 101surrounding the pin 9S bears at one end against a washer 1t2 carried bythe pin and at the other end against an internal boss MP3 to yieldinglyurge the pin inwardly of the base so that the inner end thereof mayenter and is yieldingly held in a selected opening 25' of the guide bar.A handle or knob ldd is provided on the outer end of the locking pin 98to facilitate manipulation of the latter, and the inner end of the pinis tapered at 19S. The taper 105 of the pin and the. bell-mouth shape 96of the holes are so relatively shaped and proportioned thatsubstantially line contact therebetween is established, at a positiondisposed well inwardly of the ends of the holes, so that accuratealignment of the indexing bar will be effected as will be referred tolater. Adjacent its outer end, the locking pin 98 is provided with anannular groove 106 adapted to receive a detent plunger 167 slidablydisposed in the boss M3, radially of the locking pin, for yieldinglyretaining the locking pin in retracted position (to the left, Fig. 4).The detent plunger MW is biased upwardly or toward the locking pin bymeans of a leaf spring S solidly anchored at its inner end by suitablemeans and with its outer end normally biased upwardly and engaging thedetent plunger. When the locking is retracted and the gro-ove 106 is inregister with the detent 107, the latter is biased upwardly into thegroove and releasably retains the locking pin in retracted position. Thegroove and detent have interengaging surfaces acting as camming surfaceseffective to retract the detent in response to pressure applied to thepin for that purpose. When the locking pin is in such retracted positionits inner end is clear of the holes enabling sliding movement of theguide bar or indexing bar 94 for selectively positioning the holes 95for reception of the pin.

The rib 92 is aiso provided with a recess 109 (Figs. 4 and 5) openingupwardly through the upper surface bed plate. Removably disposed in therecess M39 is a leaf spring 110 engaging at its ends with pins 111 xedin the floor of the recess and engaging at its central portion with aball M2 located in an aperture 113 which opens through from the recess199m the groove 93, and which is in alignment with the locking pin 98.The aperture is of appropriate size to enable free movement of the balland the ball is of such a diameter that it enters into the taperedportions 97 of the holes 95 only to a slight extent (Fics. 4 and 5). Theleaf spring biases the ball toward the indexing bar 94 and when any oneof the holes 9:3 is in register with the ball the latter is biased so asto enter the hole to a slight amount, whereby in the movement4 of thecarriage as hereinafter explained, the operator experinces a Feel thatone of the holes 95 is engaged by the ball and hence is in register withthe locking pin 9S for receiving the latter. Preferably the leaf springil@ can be removed merely by gripping and lifting it out and it isrestrained against longitudinal movement by the end walls of the recess,and normally against upward removal by the adjacent element of thecarriage 33.

The retention of the locking pin in retracted position eliminateschattering of the locking pin in engaging the holes, as when theoperator would retract the pin and release it when the carriage andindexing bar is moved, and consequent wearing of the edge surfaces ofthe holes. The ball 112 is normally effective to retain the indexing barin the selected position by engagement with the corresponding hole, butif for any reason the selected hole is not accurately aligned with theVlocking pin, the tapered surface on the pin will engage the bell-mouthsurface on the hole and produce a camming effect on the indexing har andmove it to accurate position. The ball enters the hole to such a slightextent that only relatively ilat camming surfaces are establishedtherebetween. Any wearing or mutilation that may occur on the edgesurfaces of the holes will not affect the desired line contactengagement between the pin and hole, and accurate alignment of theindexing bar is thus obtained.

In order that the operator may determine `which index hote 9S is inregister with the end of the locking pin 9S, a reference mark M3 (Eig.l) is provided on the carriage S3 and cooperates with the index scale M4which for convenience may be provided on the machine name plate M5 whichmay be attached to the side wall 14. The carriage 83 is operativelyconnected to the indexing bar 9d so that it is maintained in adjustedposition on the base l@ as determined by the position of the indexingbar 94. To this end the indexing bar 94 (Fig. 6) is normally urgedtoward the forward end of the carriage 83 by a compression spring 116centered on a pin 117 projecting inwardly from the rear end of thecarriage F13 and bearing against the rear end of the indexing bar 94. Amicrometer adjusting screw 1.13 of novel construction is provided at thefront end of the carriage in position to be abutted by forward end ofthe indexing bar and serves to determine the forward position of theindexing bar relatively to the carriage.

"f he indexing holes 95 are so located on the indexing bar 9d as toestablish spaced predetermined positions of the carriage 33 on the base.1.0 and accordingly to establish corresponding predetermined positionsof the pivot axis of the carriage 87 relative to the surface of thegrinding element 47. In the present illustrative embodiment the indexingholes 95 are spaced apart on one-half inch centers and are so located asto determine positions of the aforesaid pivot axis spaced from thegrinding element 47, ranging from 41/2 inches to 8 inches. The

several indexing holes 95 are labeled respectively with indiciarepresenting diameters corresponding to the respective radii which theholes establish as above explained. For example, the hole 95 at theright hand end of the series (as viewed in Fig. 6) is so located thatwhen the carriage is in the position in which that hole is in registrywith the locking pin 9S and the screw 118 is in its zero position, thepivot axis of the carriage is exactly 41/2 inches from the surface ofthe grinding element.

The adjusting screw 118 is -made up of relatively adjustable elementsenabling its setting to an accurate Zero indicating position, therebyeliminating the necessity for extreme accuracy in this respect in themanufacture thereof. The adjusting screw 118 includes a shank 119threaded on its outer end portion and preferably provided with a screwdriver slot. The inner end is threaded into a bushing 126 suitablysecured stationarily in a bore 121 of the carriage in longitudinalalignment with the indexing bar 94. The innermost end portion of theshank is preferably of reduced diameter at 122 and fitted with a sleevebushing 123 slidable and rotatable relatively to the outer bushing 120.The inner end of the shank engages the indexing bar and serves toprovide relative movement between the carriage and indexing bar uponappropriate turning of the adjusting screw. The adjusting screw 113includes a knob 124 having a radial flange portion and a sleeve portionthreaded on the shank and provided with a set screw 12S for engagementwith the shank for adjustably setting the knob relative to the shank.The adjusting screw also includes a sleeve 126 telescoped with thesleeve portion of the knob and also provided with a set screw forengagement with the knob for releasably securing the two elementstogether in adjusted relation. The bushing 120 is provided with indiciamarkings (Fig. 2) including an axial line 12S and axially spaced lines129. The sleeve 126 is provided with circumferentially spaced markings130 cooperating with the markings 128 and 129 on the bushing.

For the purpose of making the initial adjustment of the adjusting screw118 so that it accurately indicates the adjustment made thereby, theindexing bar 94 is moved to any arbitrary position, for example, to a9-inch position in which the locking pin 98 enters in the 9-inch hole,i. e., the hole at the far right (Fig. 6). At such position of theindexing bar and at the zero position of the adjusting screw 11S theaxis of the pin 170 is to be exactly four and one-half inches from thesurface of the abrasive sleeve 51, a measurement in practice obtained bygauging the distance between the axis of the pin 176 and the axis of thegrinding element. if, however, the distance between the axes mentionedis not as indicated the operator threads the adjusting screw 118 to theposition in which that distance is as desired. Turning of the adjustingscrew moves the carriage relative to the indexing bar 94- which islocated relative to the base and thereby the carriage is moved relativeto the grinding element. Thereafter the operator applies a screwdriverto the slot in the shank 119 and after loosening the set screw 125rotates the knob 12d until the edge of the sleeve 126 registers with theappropriate indicia marking 129 and then tightens the set screw 125. Ifthe zero marking of the index 139 is not then in register with the line12S for indicating the zero position, the operator loosens the set screw127 and rotates the sleeve 126 relative to the knob until such zeroposition is indicated. The set screw 127 is then tightened. The knob 12dand sleeve 126 thereafter form an effectively integral part. The inneredge of the sleeve 126 thus serves as an indexing line or indicia mark.lt is to be understood, of course, that rotation of the sleeve 126relative to the knob does not produce any axial movement of the sleeverelative to'theknob, and upon setting of the shank 119,

setting of the knob 124 'tixes the axial position of the adjusting screwand securement of the sleeve on the knob iixes the sleeve and therebythe assembled adjusting screw in circumferential or rotational directionwith respect to -the zero position. The construction of the adjustingscrew 118 eliminates the necessity for justifying the threads on thescrew and provides a simple and effective means for making the properinitial accurate setting.

Means are provided for securely locking the carriage 83 to the bed plate22 in any one of its indexed or adjusted positions, To this end alocking assembly is provided which includes clamp shoe 131 (Figs. 4 and6) tiltably supported on a collar 132 which is supported on an adjustingnut 133 threadedly received on the lower end of a stud 134, the otherend of which is threadedly received in the carriage 53. A thrust pin 136has its lower end seated in a depression 138 provided in the clamp shoe131 and has a portion 140 thereof threadedly received in the carriage83. A handle 142 is i'lxedly received in the head 144 of the thrust pin136 and is adapted to be swung from the full line position thereofindicated in Fig. 2, wherein it is in engagement with a limit stop orabutment 146, to a dotted line position wherein it is in engagement withan abutment 148. In the full line position of the handle 142, the clampshoe 131 has its clamping surface .159 in light engagement with theunderneath surface of the bed plate 22 while in the dotted llineposition of the handle 142 the clamping surface bears rmly against theunderneath surface of the top wall 22 of the oase if! and serves to lockthe carriage 83 in its desired position of adjustment. The rib 92 isprovided with a longitudinally extending slot through which the stud 134and pin 136 extend, enabling sliding movement of the carriage.

A headed pivot pin 176 (Fig. 6) in the form of a shoulder bolt extendsthrough and is secured to the carriage S3 centrally of the bed surfaceS5 thereof as by a nut 171 and passes through bosses 172 and 174,provided on the carriage 33 and on the turntable S6 respectively, andserves to center the turntable S6 on the bed 3;'- while permittingturning movement of the carriage 87 as a whole about the axis of thebolt 170, which is the pivot axis above mentioned. l' n the manufactureof the device, the head of the bolt 179 is held to close tolerances andaccurate concentricity relative to the shank, so as to provide anaccurate reference point for the initial setting of the device.

The carriage 87 includes an upstanding portion 176 having a pair oftransversely spaced bearings 178 formed therein each of which mayconsist of longitudinally spaced portions formed in opposite wallmembers or the portion 176` The bearings 176 respectively receivetherein elongated rods or supporting bars 188 for longitudinal slidingmovement of the rods or supporting bars in the bearings and consequentmovement of the brake shoe holder 88 to be later described, toward andfrom the grinding element relative to any given xcd position of thecarriage 33.

The brake shoe holder or chuck 88 (sec Figs. 6, 8 and 9) includes alower clamp or supporting bracket 192 having transversely spacedportions 193 (Figs. 2 and 8) each of which has a tubular element 1.94receiving the rear end of one of the supporting bars 13S and securedthereto by means of a set screw 195, so as to be movable unitarily withthe supporting bars.

The supporting bracket 192, which may bc formed as a casting, includes alower, generally T-shaped portion 196 (Fig. 8) which has formed thereonat spaced points a pair of bosses 198, each having an upstanding rib orpad 2&5 designed for reception thereon of the arcuate center llange F ofa brake shoe BS, the lining L of which is to be ground. A locating pin199 extends through each boss 198 and is adapted to be adjustablysecured in position therein as by means of a set screw 201. The locatingpins 199 preferably have tapered ends l201 adapted to engage the innersurface of the brakeshoe rim R at spaced points therealong when thebrake shoe is placed in the holder to properly position the brake shoetherein.

The supporting bracket 192 is provided with an overlying portion 200including a threaded boss 202 which receives therein the threaded end ofa clamping stud 204. An upper clamp or clamping head 206 slidable onclamping stud 204 is provided with an apron 210 which encloses the boss202 and certain other elements hereinafter described, and a pair ofspaced toes 212 formed at spaced points at its` rear end and disposedabove and in alignment with the pads 205 for clamping engagement withthe upper surface of the ilange F of the brake shoe to be processed. Theclamping stud 204i passes through a boss 214 formed on the head 206 andis provided with a manipulating knob 216 by means of which the head 2damay be moved downwardly to bring the toes 212 into clamping engagementwith the flange F of the brake shoe. A spring 218 disposed between theapron 210 and overlying portion 200 of the supporting bracket 292 servesto yieldingly urge the movable head 266 toward open position relativelyto the supporting bracket 192.

The portion 196 is also provided with a third upstanding rib or pad 203located intermediate the two outer pads S, the upper surface of the pad203 and the upper surfaces of the pads 205 lying in a common planeperpendicular to the abrasive surface. The pad 203 and the two pads 205are disposed generally along the arc of a circle and are so located thatwhen any brake shoe within the range of sizes which the holder isdesigned to accommodate is disposed in position in the holder, theflange of such brake shoe is engaged by the three pads 203 and 205 atpoints approximately equidistant from the rim, which points lie in theaforementioned plane which is perpendicular to the abrasive surface.Accordingly, and as will appear hereinafter, any brake shoe within theaforesaid range of sizes will be supported in position with its brakingsurface extending substantially vertically and therefore substantiallyparallel to the abrasive surface of the grinder.

In the case of many conventional brake shoes the flange extends with itsmedial plane perpendicular to the exposed braking surface of the brakeshoe lining, but since the ilange increases in thickness in a directionfrom the rim toward the inner edge of the llange, the faces of theflange therefore are not planar and are not parallel to the medial planeof the flange but are portions of cones and diverge from the rim and areinclined to the medial plane. Accordingly, if the brake shoe weresupported in the grinder of this invention with one face of the flangeclamped against a flat, horizontal surface, or two spaced surfaces,extending over a substantial portion Vof the radial length of theflange, or three surfaces not equidistant from the rim, the brake shoewould be positioned with its medial plane inclined to the abrasivevsurface and consequently the exposed braking surface would also beinclined to the abrasive surface. However, in the holder of the presentinvention the ilange of the brake shoe is clamped against threeV spacedsupporting surfaces of relatively narrow extent (measured in a directionradially of the brake shoe) and the surfaces are so arranged that theyengage the brake shoe at three spaced points approximatelyequidistantfrom the rim. Since, as aforesaid, the three supporting surfaces lie ina plane normal to the abrasive surface the `brake shoe is thereforesupportedwith its exposed braking surface, extending substantiallyparallel to the abrasive surface, i. e., in a position that may be, forpractical purposes, considered parallel, because the` variation fromparallel arrangement in any particular case would be negligible. lnorder to permit the holder to accommodate brake shoes of various radii,as for example brake shoes for brake drums having diameters ranging from9 to 16 inches, the pads are disposed so that they engage l0 any brakeshoe Within the aforesaid range of sizes at points which areapproximately equidistant from the rim.

Referring now to Fig. 8 wherein there is shown somewhat diagrammaticallythe relative positions of two brake shoes in position in the holder,namely, the smallest standard brake shoe BS and the largest standardbrake shoe BS, respectively. lt will be noted that the two outer pads205 are positioned to engage the ilanges F' and F" of the respectivebrake shoes BS and BS at points along lines C and C representing arcsdrawn about the centers of curvature of the rims R and R of the brakeshoes BS and BS, respectively, and passing along the flanges F and Fintermediate the rims R and R and the inner edges of the flanges F andF. The center pad 203 is positioned to engage the flanges at a point oneach flange respectively between the arcs C and C. Accordingly, whilethe center pad 203 does not engage either ilange at precisely on the arcdrawn about the center of curvature it does engage each ilange at apoint sufficiently close to such arc that the error thus resulting doesnot seriously affect the proper positioning of the brake shoe in theholder.

While the holder has been described with particular reference to its usein connection with brake shoes having tapered flanges, it will beapparent that it is also suitable for use with brake shoes havingflanges of uniform thickness.

Means are provided for adjustably positioning the supporting bars 15Sand the holder 8d relatively to the pivoted carriage S7 and for rockingthe latter about its pivot. Such means includes a tubular socket memberor block 222 of externally square cross-section, tiltably mounted upon arock shaft 208 and provided with a cylindrical bore 224 therein adaptedto receive one end of an elongated operating rod 226. The rock shaft 20Sextends between and is supported in a pair of forwardly extending sideilanges 22@ (Figs. 6, 8 and 9) formed on the supporting bracket 92. rlherear end of the rod 226 is provided with an annular groove 228therearound and the rock shaft 2% passes through the socket member 222in such a manner that it enters the groove 22S and serves as a lockingpin for holding the end of the operating rod 22o within the bore 22d1 ofthe socket member 222 against longitudinal or axial shifting movementwhile at the same time permitting free turning movement of the rod 226relative to the socket member 222.

From the above description of parts it will be seen that the rock shaft2da serves the functions of tiltably supporting the socket member 222`and of holding the end of the operating rod 226 within the bore 224 ofthe socket member 222.

The operating rod 226 extends forwardly of the brake shoe supportingassembly to overlie the forward end of the machine and is provided withthreads 230 throughout the major portion of its length. A handle 232(Fig. l) is secured on the forward end of the rod 226 in order that anoperator may impart turning movements to the rod as well as to oscillatethe same from side to side. The threaded portion 230 of the red 226 isadapted to be received in a half-nut structure 234 provided on thecarriage 37 by virtue of a pair of upstanding members or ears235 (Figs.2 and 3) which define therebetween a semicircular threaded bore 233, thethreads of which are designed for cooperation with the threads 230 onthe rod 226. The flat sides of the socket 222 cooperate with the sideflanges 220 to constitute means for maintaining the threaded portion 230of the rod 226 in vertical alignment with the half-nut 234 so that upondownward swinging movement of the rod 226 in any position of theturntable the threaded portion 230 will fall into register automaticallywith the half-nut 23d.

Since the rod 22:5, by virtue of its reception in the socket member 222is pivoted for rocking movement about the axis of the rock shaft 2tlg ina vertical plane,

it will be seenthat the operator may at will lift the rod 226 out .ofthehalf-nut structure 234 to disengage the same therefrom and by .applyinga thrust or a pull to the rod 226, as the case may be, slide theholderv88 and the supporting bars 188 as a unit longitudinally of themachine toward and away from .the grinder 47. Such Vsliding movement ofthe holder 88 by the application of a thrust or a pull to the rod 226provides a fast or coarse adjustment for the purpose of advancing abrake shoe into initial grinding relation with respect to the grindingwheel 47. When the lining L of the brake shoe has been brought intoclose proximity to the surface of the grinding wheel 47, a fineadjustment may be made by lowering the operating rod v226 into thehalf-nut 234- for engagement between the threads thereof with thethreads 230 on the rod, after which turning movement of the handle 232in one direction or the other will feed the holder 88, together with thebrake shoe supported thereon, toward the cylindrical grinding wheel 47for grinding purposes. A scale A227, gradulated in thousandths of aninch, isprovided on the rod or feed screw 226 and cooperates with areference mark 229 on the socket member 222 to indicate the extent ofthe feed just described.

It has been found that the operator when swinging the rod`226 to rockthe carriageS about its pivot (as hereinafter explained) often tends toturn the rod 226 unintentionally about its axis and thereby advance orretract the brake shoe holder. Accordingly, I preferably providesuitable friction means for inhibiting such turning movement of the rod226 relatively to the half-nut 234. To this end I preferably form a bore235 in the end portion of the rod 226 and dispose therein two bearing.balls 237 which are yieldingly urged into engagement with the Wall ofthe bore224 by a coil spring 239 with sufficient force to provide thedesired resistance to turning movement of the rod in the socket 222.

The provision of the transversely spaced rods or supporting bars 188provides great stability of the brake shoe holder 88 so that it will notrock or tilt about a longitudinal axis. This accurate positioning of thebrake shoe holder together with the accurate shape and dimensions of the.grinding element assure that the brake shoe lining will be ground andfinished toa surface of truly cylindrical form. Furthermore, there is'norocking movement of the brake shoe holder about a transverse axis.

To illustrate the operation of the apparatus in processing the lining Lof a standard vbrake shoe BS in new condition, it may be assumed that a9 inch brake shoe is to be processed for use with a brake drum which isexactly 9 inches in diameter. Thus for effective processing of thelining L, grinding operations on a 41/2 inch radius will have to beperformed so that the surface of the brake shoe lining will have anarcuate contour formed with a 41/2 inch radius. It is necessary,therefore, that during the grinding operation the distance from thepivot axis of the carriage 87 (Fig. 6) to the periphery of the grindingsurface of the grinding wheel 47 be 41/2 inches. With the handle 142 inits full line position (as shown in Fig. 2), the clamp shoe 131 is freeand the carriage 83 is capable of free sliding movement on the bed plateor top wall 22 of the base 10. Inasmuch as the brake shoe is to beground to a 41/2 inch radius no adjustments of the adjusting screw 118(Fig. 6) are necessary other than to ascertain the fact that the scale130 is at its zero position.

The end of the indexing locking pin 98 is retracted and the carriage 83is moved to an approximate position wherein the opening or hole 95labeled 9 is brought into register with the locking pin 98 (Fig. 5),after which release of the pin 98 will permit the spring 101 to urge thepin inwardly into the opening 95 to index the carriage 83 to its properposition for grinding on a 41/2 inch radius. To lock the carriage 83securely in this position the handle 142 is moved from its full lineposition to its dotted line position (as shown in Fig. 2), so that thethrust pin 136 engages Vthe depression 138 provided in the clamp shoe131 to tilt the shoe in a clockwise direction (as viewed in Fig. 6), andthus bind the carriage 33 and base v1) against relative displacement.

Prior to the grinding operation it is, of course, necessary to properlyposition a brake shoe of the desired size in the holder 88 andaccordingly the knob 216 is manipulated to back od the clamping stud 204to move clamping jaws2i2 away from the bosses 198 after which time abrake shoe BS is positioned in the holder with the angc F resting on thesurfaces of the pads 293 and 20S and with the locating pins 199 engagingthe inner surface of the rim -R at spaced points. Tightening ol' theknob 216 will serve to move the clamping head 206 downwardly and causethe jaws 212 to engage the iiange F and clamp the same against surfacesof the pads 203 and 205 in proper position for grinding the liningL ofthe brake shoe. The brake shoe is positioned in the holder by abutmentwith the two pins 199 which are so located that the surfaceof the brakeshoe is concentric with the pivot axis of the carriage 87 and thesurface of the lining L is closely parallel to the abrasive surface ofthe grinding wheel 47. Accordingly when the carriage 37 is rocked aboutits pivot axis, with a brake shoe positioned in the holder 88, the brakeshoe surface moves about such axis in a true circular path.

.With the brake shoe BS thus positioned in proper alignment with thegrinding wheel 47, the holder 88 may, by a fast adjustment ,aspreviously described, be brought to a position wherein the lining L isbrought into close proximity with the abrading surface of the grindingwheel 47. To accomplish this the operating rod 226 is manually tiltedupwardly about its pivotal axis of support on the shaft.208 so that thethreaded portion 230 of the operating rod is removed from the half-nutstructure after which, by exertinga manual thrust on .the rod 226 holder8S is advanced until the surface of the lining L closely approaches thegrinding surface of the grinding -wheel 47. At this time the threadedportion 230 of the operating rod is lowered into the half-nut structure234 to secure the holder 88 in position. With the brake shoe lining L inclose proximity to the cylindrical grinding surface of thegrinding wheel47 and with the threaded portion 230 of the rod 226 located within thehalf-nut structure1234, the operator may, by rotating the rod'226 in aclockwise direction (as viewed in Fig. 3), accurately feed thelining Ltoward the rotating grinding Wheel.

For any setting (i. e. position of adjustment) of the carriage 83 on'the base 10, the distance from the center of the pivot pin to thenearest portion of the surface of the grinding .element 47 remainsconstant. Hence, all points ony thesurface of a brake shoe which are ata distancefrom the center of the pivot Vpin equal to the distancebetween 'thevcenter of the pin and the surface of the grinding elementwill, when the holder 88 is rocked about the-pivot pin, move ,in an archaving a radius of curvature equal to the distance between the center ofthe pivot pin and the surface of the grinding element. When the rod 226is swung from side to side and rotated to impart feed movement to theholder 88, the surface of the' liningwill be dressed down by thegrinding wheel to a true circular arc having a radius of curvaturecorresponding to the setting of the indexing means. Screw feedy movementof the rod 226 in a direction toward and away from the grinding elementregulates the amount of material removed.

1n certain instances the operator may wish to dress the liningdown apredetermined amount or to determine exactlyto .what extent the lininghas been dressed down. The vdistance that the holder ismoved by the tinescrew feed, and thus the extent the lining has been dressed down, may;bedetermined by observing the scale 227 on the rod 226:;with-refercnce tothe-index mark 229 on the socket member 222.

In processing brakes it is often found that the drum had been badlyscored and that in order to provide a true cylindrical braking surfacethe drum has to be bored out to make its surface truly cylindrical. Thebrake shoe must be relined and dressed accordingly. If, for example, adepth of 0.060 inch of metal is removed from a inch diameter drumthereby increasing the drum diameter by twice that amount, it isapparent that the dressing procedure on an oversize new lining providedon the original brake shoe Vwould have to be conducted with the grindingtaking place on a radius of 0.060 inch greater than the tine radius ofthe original standard drum and brake shoe. In such case it is necessaryto adjust the sliding carriage 83 so that the pivot axis of the pivotedcarriage 87 assumes a position 5.060 inches from the surface of thegrinding wheel 47, whereby, upon oscillation of the carriage 87 duringthe grinding operation, the radius of the path of movement of thedressed surface of the lining will be 5.060 inches.

To provide for the grinding of a brake shoe lining L on such an oversizeradius of curvature as that given in the example outlined above, it ismerely necessary for the operator to index the carriage 83 by moving itto the appropriate position wherein the second hole of the series(reading from right to left in Fig. 6) is in registry with the pin 98and permitting the pin to enter the hole, and to move the adjustingscrew 11S to'a position wherein the 0.120 index is indicated. Thislatterv adjustment is attained by Va clockwise movement of the adjustingscrew which feeds the adjusting screw inwardly of the carriage. The endof the adjusting screw thus bears against the end of the indexing bar 94and draws the carriage forwardly the desired 0.060 inch distance. Thegrinding of the lining L on the 5.060 inch radius may then take place inthe mannerpreviously described by oscillation'of the"rod 226 from sideto side.

From the above description, it will be noted that the indexing bar`effectively becomes a part of the carriage when the bar moves with thecarriage in vinitially adjusting the carriage according to the positionsdetermined by the holes 95; and it effectively becomes a part of thebase when it is locked by the pin 98 and the carriage is adjustedrelative to the indexing bar by means of the adjusting screw 118.

The device of the present invention provides convenient means forforming a bevel on each end of the brake shoe lining by a simplemanipulation of the operating rod 226 and without changing the settingof the carriage 37. To form such bevel, the operating rod is raised outof engagement with the half-nut and the carriage 87 swung to a positionwherein one end of the brake shoe lining is opposite the grinder 47. Byappropriate manipulation of the rod 226, the holder 8% is then movedrearwardly without swinging movement to push the end of the brake shoelining against the surface of the grinder 47 and thereby grind a bevelon the end of the lining. The holder 8S is then backed on and swung to aposition to bring the other end of the lining opposite the grinderwhereupon the beveling operation is repeated in respect to that end ofthe lining.

From the foregoing it will be seen that the present invention provides agrinding device which is especially well adapted for grinding linedbrake shoes to true arcuate contour, which is simple in construction,and which may be made economically. At the same time, however, thedevice is rugged and sturdy and can be used for a long out of lockingengagement with said indexing bar in any of a number of positions of theindexing bar, said locking means having a recess Ytherein detent means,and means resiliently urging said detent means into engagement Ywithsaid locking means, said detent means registering with said recess insaid locking means in the non-locking position of the latter andoperative for releasably retaining said locking means out of lockingposition.

2. A grinder comprising a base, a grinding element supported on saidbase, a carriage means supported on said base, a holder for an articleto be ground supported on said carriage means, said carriage means beingslidable on the base toward and from said grinding element and having aplurality of locking elements spacedl longitudinally along the line ofits movement, locking means mounted in said base for movement into andout of locking engagement selectively with said locking elementsaccording to the adjusted position of said carriage means, spring meansbiasing said locking means toward the position of locking engagement,said locking means having a recess therein detent means, and meansresiliently urging said detent means into engagement with said lockingmeans, said detent means registering with said recess in said lockingmeans in the non-locking position of the latter and operative forretaining said locking means out of locking position against the actionof said spring means, said recess in said locking means and said detentmeans including cooperating camming surfaces effective for moving saiddetent means to releasing position in response to pressure applied tosaid locking means in excess of that exerted by said spring means in thedirection of locking engagement.

3. Locking means for a device having a base and a member mounted on thebase for sliding movement thereon, comprising a plurality of lockingelements on the movable member at predetermined spaced locations alongthe line of movement, a plunger mounted in said base for slidingmovement in directions transverse to the line of movement of the movablemember into and out of engagement selectively with said locking elementsfor locking the movable member in adjusted position, spring meansbiasing said plunger toward locking position, said plunger having arecess in its periphery, detent means mounted in said base for slidingmovement into and out of position engaging the surface of said recess,and spring means biasing said detent means toward its said position,said detent means and two opposite surfaces of said recess havinginterengageable camming surfaces loperative for moving said detent meansout of said recess in response to a force applied to said plunger ineither direction in excess of the holding force exerted by the rstspring means.

4. A grinder comprising a base, a carriage mounted on the base forsliding movement thereon, an indexing bar slidable on said base andengaging said carriage for posi-V tioning the latter on said base, saidbar having a plurality oi holes extending transversely therethrough atpredetermined spaced intervals along the line of movement of thecarriage, said holes having outwardly diverging surfaces on one side ofthe bar, a pin slidably mounted in said base on one side of the indexingbar, having a tapered end engageable selectively with the divergingsurfaces of said holes and operative for locking said carriage againstmovement, a ball `mounted in said base on the other side of the indexingbar in alignment with said pin for movement into and out of engagementselectively with the edges of said holes and being dimensionedrelatively to the holes so as to extend thereinto a slight extent andpresent surfaces in engagement with the edges of the holes of suchinclination as to enable the ball to be forced out of the holes inresponseto movement of the carriage, and spring means biasing said balltoward the index bar.

5. A device of the character disclosed comprising a base, a carriageslidably mounted on said base, said carriage having an element extendingalong its line of movement provided with a plurality of holes spacedlongitudinally therealong at predetermined intervals, said base having acavity and an rapertureethrough a wall of the cavity adapted to alignselectively with .said holes according to the position ofthe carriage, aball in said 4aperture of greater diameter than the holes,longitudinally spaced pins in the cavity positionedon opposite sides `ofsaid aperture, and a leaf spring interposed between saidpins and balland operative for biasing the ball toward thesaidcarriage element havingsaid holes.

6. A grinding device comprising a base, a grinding element mounted onsaid base, .a carriage mounted on said base for sliding movement towardzand from said grinding element, an indexing bar mounted n saidbaseforsliding movement relative to said base and to said carriage, meansmounted in said base-for releasably locking said indexing bar in any ofa number of predetermined positions, means normally retaining saidcarriage in engagement with said indexing bar for movement therewith,VVand means for adjustably moving said carriage Irelatively to saidindexing bar, said last means comprising an element on said carriagehaving an laxially yextending zero indicia `mark -and axially `spacedgraduatedindicia marks, a screw threadedly mounted in said vcarriage inengagement with said indexing bar, a knob threadedly mountedon ysaidscrew and having indicia ,means .with a circumferentially extendingindicia mark and circumferentially spaced indicia marks, said knob beingadjustable axially of said screw, and said indicia means beingadjustable rotationally of the knob in fixed position axially thereof.

7. A grinding element comprising a spindle adapted for rotationalmounting, a cylindrical inner .sleeve of relatively rigid, resilientmaterial having alongitudinal slot enabling limited expansionthereofinradial direction and thereby having a normal diameter and an expandeddiameter, a-seamless abrasive sleeve surrounding said inner sleeve of adiameter within the limits ofdiametrical dimensions of the inner sleeve,and `a pair of .endmembers mounted on the spindle havingcamming surfaceson their inner ends for engaging the inner sleeve and expanding it intodirect frictional engagement with the abrasive sleeve throughout thelength of the latter, cylindrical surfaces axially outwardly of saidcamming surfaces, and radial shoulders axially outwardlyfof saidcylindrical surfaces engageable with the ends of the sleeves, saidspindle extending through one of said end members, and the other endmember having a recess receiving an end portion of the spindle, andscrew means extending through said other end member and threaded intosaid end of the spindle, said screw means having a head engaging theouter surface of the end member and a shoulder engageable with the innersurface of the end member for positively removing the end member fromthe assembly in response to removal of the screw means from the spindle.

References Cited inthe le of this patent UNITED STATES PATENTS 282,509Fearey Aug. 7, 1883 343,478 McArthur June 8, 1886 580,665 Goshorn Apr.13, 1897 599,245 Merrill Feb. 15, 1898 937,480 Smith et al. Oct. 19,1909 1,101,171 Fischer June 23, 1914 1,282,030 Benemelis Oct. 22, 19181,706,644 Woernle Mar. 26, 1929 1,883,747 Maddox Oct. 18, 1932 2,083,793Price June 15, 1937 2,102,915 Rishel Dec. 21, 1937 2,225,806 Stone Dec.24, 1940 2,345,161 Thomason Mar. 28, 1944 2,429,752 Greulach Oct. 28,1947 2,580,865 Wallen Jan. 1, 1952 2,637,145 Wasley May 5, 1953 FOREIGNPATENTS 378,974 Germany Aug. 9, 1923 .crema

